Radiant Panel with Varied Channel Geometries for Enhanced Retention of Tubing

ABSTRACT

A radiant panel having a U-shaped channel or groove with substantially parallel vertical sides. Because varied diameter tubing pressed into curved channels of varying radius will change their shape from round to oval by different amounts, channel width will be reduced at curved channel areas as appropriate, based on tubing size and channel radius. This reduction in curved channel width compared to straight channel width allows for a consistent friction force to be developed upon pressing the tubing into a channel. The depth of groove may be varied to allow for the increased vertical dimension of tubing which is deformed from round to oval by bending forces, so that tubing can be installed consistently flush with the surface of the radiant panel. Varying width and depth will also tend to maximize the contact area of tube to conductive surface, thereby improving the flow of heat from tube to radiant panel.

RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/235,539, filed on Aug. 12, 2016, which claims priority fromU.S. Provisional Application No. 62/204,766 filed on Aug. 13, 2015, bothof which are incorporated by reference herein in their entireties.

FIELD

The features described herein relate to the channel configuration ofmodular radiant heating panels.

BACKGROUND

Hydronic radiant panel heating is a popular form of heating forhabitable structures. This form of heating typically incorporates tubingcarrying a heated fluid, that transfers heat from the tubing to a panel,which then conducts that heat across the surface of the panel, therebytransferring heat to the habitable space within the structure. Thesepanels are most commonly a part of a floor assembly but can also be apart of wall or ceiling assemblies.

Historically, radiant panels were largely comprised of circuits oftubing forming continuous serpentine or spiraling loops embedded in aslab comprised of Portland cement concrete or gypsum based concrete.Recent developments in hydronic radiant heating have focused on arraysof modular panels that rely on aluminum or other conductive materials todistribute heat from the tubing across the surface. Some systems havebeen manufactured with the tubing already permanently secured within thepanel. In these instances, while the tubing may be securely containedwithin each panel, numerous connections must be made between individualpanels within an array in order to complete a circuit through which theheated fluid may be circulated. The inherent challenge in these systemsis that each connection adds to the labor at time of installation, andthe likelihood of leaks multiplies with the number of connections, eachof which must be accomplished without defect and maintain theirintegrity for the lifetime of the structure.

Systems seek to avoid this challenge by installing the tubing after thepanel array is installed in the structure. This allows the tubing to becontinuous, with the exception being the connections at the beginningand end of each loop, but without connections between individual panels,thereby reducing labor and the likelihood of leaks. In most of thesecontinuous loop systems, the tubing is retained in a modular system ofchannels designed to receive and securely retain the tubing in contactwith the conductive material of the panel. The conductive function ofthe panel is enhanced when the contact area of the tubing with theconductive panel is maximized.

Various forms of polymer tubing are used in these systems with a commonbeing cross-linked polyethylene often known as PEX tubing. It is in thenature of PEX, and other polymer tubing typically used, that there ismemory in the tubing. Memory is the property of polymers that causesthem to tend to return to their original molded shape after beingdeflected to from that shape. Memory causes the tubing when deflected toact like a spring. Memory tends to resist both twisting and bending.Accordingly, due to the spring-like nature, without positive means forretaining the tubing in the channels, it may become dislodged from thechannels. Virtually all of these systems incorporate features in theirsystems to keep the tubing firmly in place. The means for retaining thetubing in channels in some systems is a mechanical feature that causes anarrowing and therefore a restriction at the top of the channel causingthe tubing once pressed past the restriction, to be restrained fromreturning back pass the restriction and out of the channel. To do solimits the efficiency of forming the channel thereby driving up the costof manufacturing. Other panel systems use adhesives. While adhesiveswork, they can add cost, can be messy, and even when used, the tubingmay need to be temporarily restrained in the groove, until the adhesiveachieves a proper cured strength, adding further cost. Some systems relyon an interference fit between the tube and the channel by slightlyunder-sizing the channel relative to the tubing size so as to createfriction with the tubing, see U.S. Pat. No. 5,788,152 to Alsberg whichis incorporated by reference in its entirety herein. The problem withthis approach is that radiant heating panel systems tend to have achannel pattern, which requires the tubing to be straight in some areasof the panel and turn through an arc at other areas. When any tubing isbent into an arc, the bending forces tend to deform the tubing crosssection from its normal round profile to a more oval shape, which tendsto make the tubing narrower relative to the width of the channel wherebent and therefore have less of an interference fit or even none. Thosesystems that have relied on the interference fit have found that thetubing is not well retained at curved portions of the channels and haveused either adhesives, mechanical fastenings or both to overcome thischallenge. These approaches to a solution have caused increased laborand material costs. In some cases, use of tubing with a deformable layerwithin the wall of the tubing has been employed. Three-layeredPEX-Aluminum-PEX is a common form of this tubing used. Due to themalleability of the aluminum, this type of tubing may be better retainedthan pure polymer tubing. But such tubing is nearly twice or more of theprice of simple one layer polymer tubing. Even with the deformablelayer, retention in the channel may still be compromised.

SUMMARY OF THE EMBODIMENTS

In a typical embodiment, a channel profile is manufactured withoutrestriction at the top of the channel thereby maximizing the number ofchannel forming techniques possible for maximum manufacturingefficiency. A simple “U” shaped channel with substantially parallelvertical sides is one embodiment that achieves this purpose. The simple“U” shaped profile, without restriction at its opening, allows formachining channels in substrates with tools that rotate vertically orhorizontally or mixing the two methods for optimum manufacturing costcontrol. In those instances where a channel is molded into a substrate,the simple “U” shaped channel, as opposed to a channel with restrictionat its opening, allows for the draft essential to efficiently moldedparts.

Because varied diameter tubing pressed into curved channels of varyingradius will change their shape from round to oval by different amounts,channel width will be reduced at curved channel areas as appropriate, inlight of tubing size and channel radius. This reduction in curvedchannel width compared to straight channel width will allow for aconsistent friction force to be developed upon pressing the tubing intoa channel, for retention purposes, regardless of whether the channel isstraight or curved. In other embodiments the depth of groove may bevaried as well to allow for the increased vertical dimension of tubingwhich is deformed from round to oval by bending forces. By varying thedepth as necessary, tubing can be installed consistently flush with thesurface of the radiant panel which enhances the installation of coveringmaterials whether they may be finish floor materials or wall or ceilingfinishes. Varying width and depth as described above will also tend tomaximize the contact area of tube to conductive surface, therebyimproving the flow of heat from tube to radiant panel.

The features and advantages described in the specification are not allinclusive and, in particular, many additional features and advantageswill be apparent to one of ordinary skill in the art in view of thedrawings, specification, and claims. Moreover, it should be noted thatthe language used in the specification has been principally selected forreadability and instructional purposes, and may not have been selectedto delineate or circumscribe the subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be more fully comprehended from the following detaileddescription and accompanying drawings in which:

FIG. 1 is a section drawing through one embodiment of a radiant panelwith a channel that can be straight or curved, that has a substantiallysemicircular bottom profile with substantially vertical side profileending at a radiused intersection with the surface of the panel at theopening through which the tubing is installed

FIG. 2 is a section drawing of a substantially round tube prior to beingpressed into a straight channel

FIG. 3 is a section drawing of a tube engaging with a straight channel

FIG. 4 is a section drawing of tubing in place in a straight channelindicating the oval deformation that creates the side force andtherefore the retaining friction on the tube.

FIG. 5 Shows the normal round shape of a straight section of tubingcompared to one that has become more oval shape due to bending throughan arc.

FIGS. 6 & 6A Show the variation in channel width between straightchannels and curved channels that is provided by embodiments to ensuresimilar side force in both types of channels.

FIG. 7 Shows the relative progression of tubing shapes from one with theoriginal round shape to that of one after being pressed into a straightchannel and one after being pressed into a reduced width curved channel.

FIG. 8 Shows the increase in vertical dimension of tubing pressed into astraight channel compared to tubing pressed into a reduced width curvedchannel.

The figures depict various embodiments for purposes of illustrationonly. One skilled in the art will readily recognize from the followingdiscussion that alternative embodiments of the structures and methodsillustrated herein may be employed without departing from the principlesdescribed herein.

DETAILED DESCRIPTION

An embodiment is now described with reference to the figures where likereference numbers indicate identical or functionally similar elements.

Referring now to FIG. 1, most modular radiant panels are comprised oftwo or more materials, typically a conductive layer (1) and a supportlayer (2). The support layer may be wood, wood fiber, cementitiousmaterials, plastic, foam or various other materials capable ofperforming the support function. Because the conductive layer iscommonly aluminum sheet or other comparatively thin conductor such ascopper sheet or graphite fiber, the shape and dimension of the channels,is largely determined by the shape and dimensions of the channels in thesupport material, not the relatively conformable conductive layer.

For the purposes of this description, it will be assumed that the panelsinto which channels are formed are horizontal and the channels areformed from the top of the panel. This however does not restrict theprocess to only horizontal manufacture or for the panels to be used onlyin a horizontal position with the channel openings on top of the panel.Other orientations for the panel during manufacture or duringinstallation in a structure are of course possible. Channels may beformed in some of these materials by machining with vertically rotatingtools such as dado blades or with horizontally rotating tools such asrouter bits.

Horizontally rotating router bits can be used to form a restriction inthe channel but only if the tool enters and leaves the panel from theedge of a panel. If the router bit enters vertically into the panel,that would prevent the formation of a restriction because the router bititself would machine away the restriction upon entering and exiting thepanel from above. Router bits are by their nature much slower than otherchannel forming techniques and the computer numerically controlledrouters that employ them are expensive and complicated pieces of capitalequipment.

Dado blades, which rotate vertically, are much faster production tools.This is because they are much larger in diameter than router bits, whichallows much higher tip speeds and therefore they machine wood and othersubstrates much faster. However they are by their vertically rotatingnature incapable of creating a horizontal restriction.

With some materials capable of providing the needed support functionsuch as plastic, foam, cementitious materials or other moldablematerials, because the molding tool must be capable of being removedfrom the molded part, any form of restriction at the top of a channelwould create negative draft and therefore, inherently prevent themolding of channels.

It is for these reasons that the example of a typical “U” shaped channeldepicted in FIG. 1 is so common in the many variations of radiantpanels.

Referring now to FIG. 2, it shows the common round shape of hydronictubing (3) employed in most radiant heating systems. The round shape istypically formed by an extrusion die, as tubing is being extruded. Likemany plastics, the cross-linked polyethylene (PEX) or other polymersutilized in hydronic tubing tend to have what is termed “memory” whichresists deformation from its straight, untwisted and round configurationthat was its cured configuration immediately after extrusion.

Polymers that exhibit “memory”, when deformed, act like springs. Theydevelop internal forces that resist the deforming force. It is this“memory”, this tendency to return to the original round shape, whichcreates the side force, which produces the restraining friction thatretains the tubing in a channel in many systems. It is this “memory”,which tends to make tubing spring out of a curved channel as theinternal forces in the tubing tend to return it to its originally formedstraight configuration. It is also this “memory” that causes anytwisting that may inadvertently occur during the tubing installationprocess, to likewise cause the tubing to spring from a channel.

The polymers often utilized in forming hydronic tubing tend to beHookean in nature, as they tend to obey Hooke's law so long as thedeformations that they are subject to occur within their elastic range.As such, the side force essential to retention in channels is in linearrelationship to the deformation.

It is in part largely to offset the Hookean nature of the subjectpolymers that PEX-aluminum-PEX tubing was developed. The aluminum isquite malleable and the normal bending forces it is subjected to operatein its inelastic range. In other words, once deformed, it tends tomaintain that deformation in a non-Hookean fashion. In other words, thealuminum tends to maintain a new deformed shape and counterbalance theHookean forces that want to unbend or untwist a tube to return to itsprior unbent or untwisted configuration.

Referring now to FIGS. 3 & 4, it is seen how pressing a round tube (3)into a channel whose width is somewhat less than the diameter of thetubing, forces it into slightly deformed oval shape (4). Due to itsHookean nature, the deformation causes a side force, and thereforesufficient force of friction needed to ensure that the tube remains inthe correct position in the channel.

Referring to FIG. 5, we see the shape of a tube after being forced intoa curved configuration typical at portions of a radiant panel. We cansee that merely bending the tubing causes an oval shape (5) and adimensional change (6) similar to the round tube pressed into a straightchannel. This means that when pressed into curved channel, no additionalside force will be generated due to the placing of a curved tube into acurved channel of the same width as the straight channel.

Referring to FIGS. 6 and 6A, which is a view of a radiant panel channelfrom above, we can see which portions of a radiant panel channel patternwill have reduced width. In embodiments this problem of reduced ornon-existent friction force is solved by reducing the width of thecurved portions of the channels by a sufficient amount (7) to have thesame or a similar degree of incremental deformation imposed on thetubing, independent of the deformation due to bending by itself prior tobeing inserted into a curved channel. Therefore the side force developedby pressing the tubing into the curved channels will be similar to theside force generated in the straight portion (8) of the channels.Because the tubing is even more ovalized than in the straight channels,this may necessitate increasing the depth of the channel as well toallow for the increase in vertical dimension of the tubing.

Referring to FIG. 7 we can see the progression of shapes fromun-deformed (3) to adequate deformation (4) in a straight section foroptimum interference fit, to adequate deformation (9) in a curvedsection for optimum interference fit.

Referring to FIG. 8, we can see the incremental increase in depth (10)required in a curved channel relative to a straight channel, for optimumtubing-to-panel contact area for efficient heat flow and to result in aflush fit with the surface of a panel.

While the one embodiment will be employed in the radiant heating panelindustry, others may make use of embodiments in other industries andapplications where straight sections combined with curved sections maytake advantage of the approximately constant side force created byvariable channel width.

Reference in the specification to “one embodiment” or to “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiments is included in at least oneembodiment. The appearances of the phrase “in one embodiment” or “anembodiment” in various places in the specification are not necessarilyall referring to the same embodiment.

While particular embodiments and applications have been illustrated anddescribed herein, it is to be understood that the embodiments are notlimited to the precise construction and components disclosed herein andthat various modifications, changes, and variations may be made in thearrangement, operation, and details of the methods and apparatuses ofthe embodiments without departing from the spirit and scope of theembodiments as defined in the appended claims.

What is claimed:
 1. A first radiant panel comprising, a groove in thefirst radiant panel, the groove having a first portion that is straightand a second portion that is curved, said groove including, a first sidehaving a first top end and a first bottom end, a second side, parallelto said first side, having a second top end and a second bottom end, arounded bottom that connects said first bottom end and said secondbottom end, wherein said first and second top end form an opening; thefirst portion having a first width selected such that a tube positionedwithin the groove is deformed by a first amount to provide a firstfrictional force between the tube and the first portion of the groove;and the second portion having a second width smaller than the firstwidth.
 2. The first radiant panel of claim 1, wherein the second widthof the second portion of the groove is selected to provide a secondfrictional force to the tube when in the second portion that is similarto the first frictional force to the tube in the first portion.
 3. Thefirst radiant panel of claim 1, wherein the groove includes a conductivelayer configured to be positioned between the first radiant panel andthe tube when the tube is positioned within the groove.
 4. The firstradiant panel of claim 3, wherein said conductive layer is aluminum. 5.The first radiant panel of claim 3, wherein said conductive layer iscopper.
 6. The first radiant panel of claim 3, wherein said conductivelayer is graphite fiber.
 7. The first radiant panel of claim 1, saidfirst portion having a first depth and said second portion having asecond depth, said second depth is larger than said first depth, saidfirst and second depths being perpendicular to a surface plane of thefirst radiant panel.
 8. The first radiant panel of claim 7, wherein saidsecond depth enables the tube to be flush with a surface plane of thefirst radiant panel when positioned within the groove.
 9. The firstradiant panel of claim 1, wherein said tube is deformed by the firstamount from a substantially circular cross section to an oval crosssection when positioned within the groove.
 10. The first radiant panelof claim 1, said first portion having a first depth and said secondportion having a second depth, said second depth is larger than saidfirst depth, said first and second depths being perpendicular to asurface plane of the first radiant panel.
 11. The first radiant panel ofclaim 10, wherein said second depth enables the tube to be flush with asurface plane of the first radiant panel when positioned within thegroove.
 12. The first radiant panel of claim 1, further comprising: asecond radiant panel, said second radiant panel comprising a straightgroove in the second radiant panel, the straight groove being straightand having a first end that abuts an end of the first portion of thefirst radiant panel.
 13. A radiant panel system comprising, a firstradiant panel having a curved groove in the first radiant panel, thecurved groove having a curved portion and having a second width; whereinsaid curved groove including, a first side having a first top end and afirst bottom end, a second side, parallel to said first side, having asecond top end and a second bottom end, a rounded bottom that connectssaid first bottom end and said second bottom end, wherein said first andsecond top end form an opening and a distance between said first andsecond top end is said second width; and a second radiant panel, saidsecond radiant panel comprising a straight groove in the second radiantpanel, the straight groove being straight, having a first width andhaving a first end that abuts the curved groove of the first radiantpanel; wherein said straight groove including, a first side having afirst top end and a first bottom end, a second side, parallel to saidfirst side, having a second top end and a second bottom end, a roundedbottom that connects said first bottom end and said second bottom end,wherein said first and second top end form an opening and a distancebetween said first and second top end is said first width; wherein thefirst width is selected such that a tube positioned within the straightgroove and the curved groove is deformed by a first amount to provide afirst frictional force between the tube and the straight groove, and thesecond width is smaller than the first width.
 14. The radiant panelsystem of claim 13, wherein an end of the curved groove has a widthsubstantially equal to the first width and the width of the curvedgroove tapers to the second width.
 15. The radiant panel system of claim13, wherein the second width of the curved groove is selected to providea second frictional force to the tube in the first radiant panel that issimilar to the first friction force to the tube in the second radiantpanel.
 16. The radiant panel system of claim 13, wherein the curvedgroove includes a conductive layer configured to be positioned betweenthe first radiant panel and the tube positioned within the straightgroove and the curved groove.
 17. The radiant panel system of claim 16,wherein said conductive layer is selected from at least one of:aluminum, copper, and graphite fiber.
 18. The radiant panel system ofclaim 13, said straight groove having a first depth and said curvedgroove having a second depth, said second depth is larger than saidfirst depth, said first and second depths being perpendicular to asurface plane of the first radiant panel.
 19. The radiant panel systemof claim 18, wherein said second depth enables the tube to be flush witha surface plane of the first radiant panel when the tube is positionedwithin the straight groove and the curved groove.
 20. The radiant panelsystem of claim 13, wherein said tube is deformed by the first amountfrom a substantially circular cross section to an oval cross sectionwhen positioned within the straight groove and the curved groove.